This invention relates to fasteners for securing shipping containers to a support platform.
Shipping containers of varying lengths from twenty to forty feet have become the standard for shipping cargo on ships, trains and trucks. These containers typically have a standard corner casting for securing the container. This casting is a cube embedded in each corner of the container with three sides exposed to the exterior of the container. The casting is hollow and has a hole in each of the three sides to receive a fastener for attaching the container to a support platform, which may be a truck chassis, a train flatbed or the deck or hold of a ship. The holes in the casting are typically shaped like an oval with two flat sides, thus having a long axis and a short axis.
One type of fastener presently used is a twist-lock type having a head shaped complementary to the hole in the casting. The head is attached to the end of a narrow neck. The head is inserted into the casting hole and then the neck is rotated. This twists the head so that its long dimension overlaps the short axis of the hole, thereby preventing it from being removed and securing it to the casting. An example of such a fastener is shown in U.S. Pat. No. 2,963,310 to Abolins. A twist-lock fastener has the advantage of being simple, but requires precise registration of the container and its corner castings with the fastener. This precise registration or alignment is sometimes difficult under actual operating conditions.
Other fasteners use a nut and bolt arrangement to attach the container to a support platform. These fasteners require a wrench and are not as simple as the twist-lock fasteners.
Hook-type fasteners are used to couple the corner castings of adjacent or stacked containers together, such as when several containers are stacked on the deck of a ship. Examples of this type of fastener are shown in U.S. Pat. No. 3,601,866 to Odin and U.S. Pat. No. 3,609,824 to Vanriet et al. Hooks have also been used as part of a nut and bolt operation with the hook being part of the bolt, such as the fastener shown in U.S. Pat. No. 3,880,090 to Duclos. A more elaborate hook-type fastener is shown in U.S. Pat. No. 3,986,460 to Voigt et al. Voigt shows a double-action hook with two opposing extended hooks which are inserted into the casting aperture and moved so that the tip of each hook exceeds the minor axis dimension of the aperture. Such a mechanism, while not requiring the precise alignment of the twist-lock type of fastener, is complex and has a large number of moving parts.